Molding compositions containing mineral fillers and products produced therefrom



United States "2,809,946 ivionuiNG oo i osmoNs' @ONTAHQHNG MIN- ERAL FFILLERS BRUDUCTSQPRODUCED THEREFROM james Bleg en, Schenectady, @N. IY;, arid .Thomas G.

"Custer,:StockliridgefMass ass'ignorsfto f General Elec- 't'ric Company, a corporation of-New York NotDraw'ing. x A-pplication NovenibenlO, 1 954, "SeriaLNp. 468,155

" ziliClaims. crass--22 QT his invention relates .to new and vnovel molding .c'ompos'itions and to .products molded therefrom. More/ par- Qticularly, this invention .relates .to .novel .resinous compo- .lsitions of matter-.and to articles.molded,therefrom,ihaving improved water. resistance and electrical ,properties -cornprising mineral fibers, a polymerized, unsaturated polyester, and-aleadsalt.

Materials usefulinfabricatingparts for electrical use must have" good-\ electrical properties rand good ,Watern'ersistance, i.-.e., \low- :water absorption. Polymer-izable, un-

saturated polyesters, becausentheyk-areg-resinous in char- ..acter before. polymerization and: fusible: ata temperature at Which polymerization is -.not rapid,.are highlyadvan- 1 tageouseas.starting materials in. the manufacture ofproducts to .be used :for electrical ,purposes. Some of the moreuseful ar-ticles tprodueedi from iunsaturated;polyesters, particularly fOIa eleetricalgjpurposea comprise an:;unsatur- .ated polyester't-and, a fibrousmaterial usually in {the \form of afiller. .:T he selactiomof 'the correcttfillertforvaygiven unsaturated i-polyester. :is of prime importance, zSlllCfi :all

Ifibrous 'materials= do :not give :satisfactory results. for;

his further dis'closed that crystalline silicate mineral fibers "belonging to the serpentine family, the most preva- "lent and most widely-used memberofv'vhichis chrysotile,

are unsatisfactory for the same purposes. The serpentines, "for example, chrysotile,- are hydrous and are therefore "distinguished from the ;pyroboles, which are anhydrous. TheWeaver patent further discloses-that while the'pyro- "boles contribute, greatly to the properties desired in-mold- 'ing compositions, materials comprising a polymerized unsaturated polyester and silicate fibers to whichhas been *added an alkaline compound, for example, zinc oxide, have-electrical properties and "water-resistance substantiaIly-better than anyofthe other products disclosed.

It now-has been-foundthatmaterialshaving superior electrical properties'andwater resistance canbe produced bytheaddition ofa' l'ead'salt to a'compos'ition comprising .a polymerized'unsaturatedpolyester"and a silicate mineral fiberbelonging to either thepyrobole or serpentine mineral-families.

In accordance withthepresent invention,'it has'been found'that if a lead salt is added to amolding composition comprising a polymerized unsaturated polyester, a silicate mineral fiber (with orwithout additionalfille'r), and an Patented Oct. 15, 1957 alkaline materiaLfor example,base s of metals o f group 'II of the periodic table, superiorwaterresistance and electfical properties are obtained. a

It was most surprising and completely unpredictable, contrary to known, prior art teaching and specifically the teaching of the Weaver patent,-that not onlythepyroboles 'but,chrysotile asbestos, if acid-washed ,prior to use, can

be used to advantage as the-silicate mineralfiber, in preparing molding compositions having excellent water re- .sistance and electrical properties. has shown that compositions prepared with acid-washed While investigation chrysotile have better proper.ties .than compositions pre- ;pared with untreated. chrysotile, even. better products ,are

obtained'by addinga-small .quantityof a lead additivein the form ofaileadsalt to the composition containingacid- Washed jchrysotile.

iThe jdiscovery thatacidawashed chrysotile can beernployed as a filler with polymerizable unsaturated polyesters inpreparingmolding. compositions is-of commercial andtecono'mic' importance, because-of its ready availability 'andlow cost. Additionally; the simple acid washing treatment .does-not.add materially to the cost of the material. .Itjhas .also .been found, in accordance with-the present :invention, that .while .the addition of a base of a group '11 metal to a molding composition comprising a polymerized, unsaturated polyestersandda filler improves certain'prop- .erties of thecompositiomforexample, its .water resistance, evenbetter propertiesmay be obtained in compoundsgof 30 this type. if. a. leadsalt is employed in [addition to the .hase.

tchrysotileiand pyrobole-typefillers.

Test,results. show this-to be the case with-both ,acid-washed Thelead salts ;-fou11 d eminently .suitable in improving It Will be obvious that the 'leadcompoundslisted are ..merelyillustrative ofatheamanyvlead 'salts coming within thei-scope-of the present invention. i Generally, the quan .[tity of: lead salt .whichmayrbe employed in::formulating the composition of {the inventionlmayrange-from. 0.5 to

about 30 percent, ;by weight ;of :the resin. 5A -.preterred percentage of leadsalttis: from zabouti2iz-to Sper cent by weight of the resin.

.As indicated earlier, materials"'found'suitable as fillers in formulating the compositions :of .theinvention may comprise a single filler, suchas acid-washed chrysotile or any one of the pyrobole types of asbestos disclosed in the Weaver patent. Additionally, another filler may be substituted for partof the asbestos filler where additional characteristics in the final product are desired, for example, added improvement in hardness, strength and surfacefinish of the polymerized material. Materials which imparthardness, strength, and superior surface finish to the .polymerizedarticles include clays, such as kaolin or china .clay; carbonatesysuch. as limestone, dolomite and whiting; :nonfibrous tsilicates such as taic; silica, etc.,- in short, all finelypowdered, inert, essentially insoluble, in organic materials may be:employed.

*Whena.silicate-fiber is-employed as the solefiller, it maybe :used intamounts'corresponding to from about 30 to90; percent, by'weightof the composition. 1Thepre ferred range of silicate fibers ,is usually, about 60't0r80 percent. .When additional filler material is employed, optimum results are obtained by using a clay, for example, in aclay to.fiber.ratio ranging from-about 0.5 :1 to 3:1. The, polymerizable .unsaturated alkyd :resins employed in the. present invention are .the reaction products of polyhydric alcohols, mixtures of polyhydric alcohols, or mixtures of polyhydric and monohydric alcohols, and an aliphatic unsaturated alpha-beta polycarboxylic acid, or a plurality of polycarboxylic and monocarboxylic acids, one of which at least is an unsaturated polycarboxylic acid. Examples of polyhydric alcohols are ethylene glycol, diand triethylene glycols, propylene glycol, butylene glycols, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, glycerine, sorbitol, trimethylol ethane, or pentaerythritol, used either alone or in combination with a monohydric alcohol. Examples of alpha unsaturated, alpha-beta polycarboxylic acids which may be employed are maleic, fumaric, itaconic, citraconic, mesaconic acids, etc. The term polycarboxylic acid as used herein is intended to include within its meaning the anhydrides of such acids. In addition to one or more of the unsaturated polycarboxylic acids, saturated polycarboxylic acids may also be present in the reaction mixture in the preparation of the resins referred to above. Examples of such saturated polycarboxylic acids are succin-ic, adipic, azelaic, sebacic, etc. a'c'ids. Additionally, aromatic polycarboxylic acids such as phthalic, tetrachlorophthalic, tetrahydrophthalic, etc., may be employed.

A typical polyester may be prepared, for example, by charging a reactor with 111 parts of phthalic anhydride, 183 parts of maleic anhydride, 169 parts of ethylene glycol, 1 part of t-butyl catechol and 4 parts of xylene. After charging, the reactor is flushed with nitrogen and heating commenced, bringing the temperature up to 150 C. in approximately 45 minutes. 25 parts of 70 percent sorbitol are then added at such a rate that addition is complete in 15 minutes. At the end of approximately 2 /2 hours, maintaining a temperature of about 190 C., 1 part of xylene is added over a -15 minute period. The temperature is allowed to rise to approximately 200 C. and 2 parts of toluene added over a -20 minute period. Approximately 2 parts of benzene are thereafter added at a temperature of about 205 C. After removal of solvents, a polyester resin is obtained having an acid value of about 35 and a cure of 2 minutes on a 200 C. hot plate. Approximately 27 parts of zinc oxide are mixed in with the polyester at about 160 C. and stirred for about to 30 minutes or until a 200 C. hot plate cure of 0.5 minute is obtained.

In addition to the unsaturated polyesters, another unsaturated compound is usually employed in formulating .molding compositions of the invention. Suitable unsaturated compounds include polymerizable monomeric compounds, such as esters of unsaturated monohydric alcohols and polycarboxylic acids, including unsaturated polycarboxylic acids, halogenated aromatic polycarboxylic acids, and polybasic inorganic acids. -Examples of such compounds are diallyl phthalate, diallyl succinate, diallyl maleate, diallyl fumarate, diallyl itoconate, diallyl chlorop'nthalate, triallyl cyanurate and triallyl phosphate. Other materials which may be incorporated with the unsaturated polyester include polymerizable esters of monohydric alcohols and unsaturated polycarboxylic acids capable of copolymerizing with unsaturated alkyd resins, such as, for example, dioctyl itaconate, dibenzyl itaconate, diethyl fumarate, and dibenzyl fumarate. Also, other polymerizable substances such as styrene, vinyl toluene, vinyl acetate, methyl methacrylate, etc. may be employed. The unsaturated polymerizable monomer may be used in an amount corresponding to from about 3 to about 50 percent, by weight of the unsaturated polyester.

Chrysotile asbestos may be rendered suitable for use in preparing the molding compositions of the invention by slurrying a mixture of chrysotile asbestos fibers and a dilute acid with mild heating. The slurry is then filtered, and the fibrous material water-washed, and reslurried in water. This operation may be repeated several times if necessary. The fibrous material is then dried at temperatures up to 125 C. As a more specific illustration, 500 grams of chrysotile asbestos floats are slurried with a 10 pieces of a soft, tacky substance resulting from hydrolytic percent excess of 1 N H2804 for approximately 70 minutes at about 52 C. The slurry is then filtered, and the filter cake water-washed twice, and reslurried in water several times. The fibrousmaterial is then dried at C. The yield of treated asbestos is approximately 84 percent. The pH of the product, measured with a standard potentiometer pH meter, using 10 grams of asbestos stirred in 100 ml. of distilled water, was 6.5 as compared to the original untreated chrysotile of 9.8. Analysis of the untreated chrysotile showed it to have a reactive alkali content of approximately 14 percent, calculated as CaO. It can be seen readily that the acid-washing process removed essentially all of the reactive alkali present in the original chrysotile.

The compounding of molding compositions of the invention may be accomplished by any one of several known methods. For example, the polyester resin, fillers and other ingredients may be mixed together to form a molding composition by means of (1) a two-roll differential speed mill, (2) by kneading or equivalent action in a Banbury mixer, a sigma-blade mixer or similar device or (3) by dissolving resin and monomer (and a conventional catalyst if desired) in a volatile solvent, mixing with the insoluble ingredient into a paste or slurry, and subsequently removing the solvent.

Molding of compositions of the invention may be accomplished by conventional compression, transfer, injection or extrusion molding techniques. Compression molding is a preferred technique using temperatures of 275-340 F. and pressures of 500-6000 p. s. i.

In the following example in which all parts and percentages are by weight, improvements realized by acidwashing of chrysotile asbestos, for example, improvement in water resistance (i. e., percent water absorption) and in exudation, are illustrated by comparison of compositions containing unwashed chrysotile and acid-washed chrysotile.

Water absorption was determined by immersing molded disks, 4 in. diameter by A3" thick, in water at room temperature for approximately 72 hours. Exudation refers to deposit on the surface of molded breakdown of the polymerized polyester resin when subjected to high humidity and elevated temperature. The

.extent of exudation was determined by confining molded pieces in an atmosphere of 100 percent relative humidity at 40 C. to 55 C. for varying periods of time, and

. observing the surface appearance.

EXAMPLE 1 A polymerizable unsaturated polyester was prepared by reacting a charge consisting of 29.9 parts of phthalic anhydride, 31.3 parts of maleic anhydride, 17.6 parts of sorbitol, 32 parts of ethylene glycol and 0.28 part of t-butyl catechol under substantially the conditions previously described.

Employing the foregoing unsaturated polyester, two compositions were prepared differing only in the fiber employed, one with untreated chrysotile, and the other with an acid-washed chrysotile. In the following formulation, filler is meant to mean either washed or unwashed chrysotile.

The foregoing formulation was compounded on a .heated two-roll differential speed mill for 25 minutes at a temperature not exceeding F. and removed in .sheet form. After cooling, the sheets were granulated in a high speed cutter. Disks A thick for water absorption and exudation testing were cured for 1 minute at 2000 lb. per sq. in. of projected area.

Water absorption was determined by immersing S molded disks in water at room temperature for approximately 72 hours. At theend of this period, the disk molded with the untreatedasbestos showed-a weight-percent gain .of 0.96 percent; as.against0.6 percent for the disk'molded' with acid-'washed chrysotile. The exudation appearance after 75 hourss of the compound containing the untreated chrysotile was bad, whereas the appearance of that containing the washed asbestos wasfair.

While the above comparison' elearly-indicatesthat the molding 1 composition containing aciii washed chrysotile is far superior to that containing unwashed 'or untreated chrysotile in water absorption, it was'foiind thatiurther "improved properties could Ebe obtained by adding *a base 7 of a metal of group; II, forexamplejjzi'nc' oxide, -t'o the composition comprising acid-washed chrysotile as illustrated in the following example, all parts and percentages Zinc 1 oxide-corresponding: to' about departs was cooked V in with the" resin 'formulationremployed in ;-Example 1. ,This resin w-as substituted for the resin in the molding composition of Example 1, andsa disk molded-inaccordance with the technique? of Example =15 was; compared to the disk of j Example 1-having acid=washed' chrysotile but 110;:Zi1'1C oxide. of-I721hours. f0? the composition containingno zinc oxide The percent-waterr-absorptiontat the -end was 0.6 asagainst 0.3;for-the same .composition containingsthe zinc-oxide. --,'lTheexudation appearanceafter 75 hours -for'zthey composition containing-inc :zinc oxide was fair, as against good for vthe composition :containing the zinc oxide. {The difierence in the water absorption of the two productsiszssubstantial and shows a decided advantage for the product containing the zinc oxide. ln -ad'd'ition' to zinc oxide; furtheriexamples .ofi bases of metals of 'group ll which may be employed inclu'debx- 'ides and "hydroxidesfof "ber yllium,-"magnesium, "calcium, 'zinc, .*s'trontiurn, cadmium and ibarium. "Generally, any

one of these bases may be used in :preparingi'thezresin in an amount corresponding to from 3 to 50 percent, by

weight oftheresin, withfromabout 141to lOrrperbntgby uveight of the .resin,.being preferred.

While themabove .examplesclearlyillustrate 'zthataax'base of a metal ofngroup. II,.for.example;tzinctoxidefimateriah *lyfiimproves the watenresistance Fof rmoldihgccorrrpounds containing acid-washedchrysotile, -it further has been found in accordance with this invention that a leadsalt of 'the type previously described: gives} even greaterf improvement. This is illustrated in""the' following example, in v vhich tribasic lead sulfate was employed as the lead 1 Manufacturedby Atlas'Powder Company.

i-Employing the resin prepared in accordance the first half of this' example and the compounding techmque of 'Example 1, two molding compositions were prepared having" the following composition:

' Composi- Composition No. 1, tion No. 2, Parts Parts Resin 26.8 26.8 Acid-washed chrysotile.-- 59.6 62.7 Blown diallyl phthalate--. 8. 6 8. 6 Calcium stearate 0.9 0. 9 Benzoyl peroxide l. 0 1. 0 Tribasic lead sulfate 3. 1

( Employing the tests d'escribed in the foregoing ex amplesgc'omposition No Lat the end of 7 2hours3showed -0.l8-' percen't water absofption as' against OB Z percent-for composition No. 2. The exudatidn appearance for-com: position No. 1 was good, whereas that for composition N0. 2 was poor.

EXAMPLE 4 {An un sautu'rated polyester "was "prepared having the renewing formulation l Percent 'Using flthisresin, twocomp'ositions wereprepared, one with=washed and one with unwashed chrysotile asbestos (indicated as filler ,as follows:

'lhe two formulations weretcompared with a commer- :cially available .alkyd moldingcornposition containing a pyrobole asbestos, specifically Blaskon .420 supplied by -.Libbey-Owens-Ford, to show that molding compositions of the invention containing an acid-washed. asbestos plus a. lead compound have-mechanical strength at. least equal to or-better than commercial grade molding compositions .prep'ared with a .pyrobole :type asbestos. The superiority of the composition containing both acidwashed asbestos and a lead compound over the composition containing the lead compound and an unwashed-as- -bestos, in both water -a bsorptionand humidity resistance, ,as well asflexural strength, is obvious. The comparisons are given in Table I.

'Table'l Unwashed Washed Commer- Fiber Chrysotile Ohrysotile cial Com- Floats Floats position disk; cure, see... 7 ,10-15 10-15 10-15 'W.A., Percent; 72 hr.-. 19 .13 j g 17 Humidity resistance Fair Good Good Flexural strength, p. s. 7. 880 8, 600 7, 990 :Tensile strength, p. s. i 3, 860 4, 010 3, 090 Izod-impact, ft. lb./in V .35 .35 .37

.T'The results Jabulated "above show -that acid-washing of "thesasbestos does notaftect mechanicalstrength, since both .tlexural. strength andtensile strength of compositions "containing -acid-washed asbestos -were --superior to the other two.tested. Thehumidityresistance and water absorptionproperties ofthe composition containing acidwashed chrysotile asbestos-arecomparable to the commereial. grade tested and better than that containing-the unwashed floats.

In the foregoing tests, flexural strength was determined by standard test procedure employing a molded bar 5" xl/z" x /2, cured forZ minutes at 2500 p. s. i. Tensile strength was .also determined by standard tensile strength specifications witha molded piece having across 7 section of 1" x A" cured for 2 minutes at 4500 p. s. i.

Izod impact strength was determined by employing a notched bar, /z x /2", cured for 2 minutes at 2500 p. s. i.

EXAMPLE 5 scribed above, and for electrical properties. Test results are listed in Table II.

Dielectric strength, power factor, and dielectric constant were determined according to standard ASTM test methods using 4" dia. x A3" thick molded disks.

EXAMPLE 6 The insulation resistances were compared of compositions containing unwashed chrysotile floats, acid-washed chrysotile floats, a composition prepared with a pyrobole type of asbestos known as Powminco 25-P supplied by the Powhatan Mining Corporation, and the commercially available alkyd molding composition of Examples 4 and 5. A resin having the following composition was employed in preparing the first three of these compositions.

Percent Phthalic anhydride 21.5 Maleic anhydride 35.5 Ethylene glycol 32.6 Sorbo (70% sorbitol) 4.8 Tert. butyl catechol 0.2 Zinc oxide 5.4

Using the foregoing resin, the three compositions were prepared having the following formulation, the asbestos being unwashed chrysotile, washed chrysotile or Powminco 25-P. a 7

Parts Resin 21.5 Diallyl phthalate (blown) 6.5 Asbestos t 15.5 Kaolin 31.0 A. A. Dolomite 15.5 Zinc oxide 7 Tribasic lead sulfate 3 Calcium stearate 1.5 Benzoyl peroxide 2 The insulation resistances of the three compositions and of the commercially available alkyd molding composition were determined by placing molded disks 4 X /2, cured. for 3 minutes at 3000 p. s. i. in sealed containers over water in an oven at approximately 70 C., these conditions being substantially 100 percent relative humidity. Results are tabulated below in Table III,

Table III Unwashed Washed Powmiuco Qommer- Fiber Floats Floats 25-1 cial Composition Insulation resistance,

megohms:

Dry 2X107 2x10 2X107 2x10 1 day 160 F., 100% RH 4X10= 1 10 7. 7X10 3X10 2 days 160 F., 100% 9 1. 4X10 4.5X10 2.4)(10 days 160 F., 100% 0.6 330 4 7da s160F.

Bier 13 18 0.4

These results show that the retention of insulation resistance of the composition containing acid-washed chrysotile asbestos was far superior at the end of the second day to that containing the unwashed asbestos, comparable to that containing the Powminco asbestos after 7 days, and superior to the commercially available molding composition tested.

In addition to improving the properties of compositions containing either acid-washed chrysotile or pyrobole type asbestos and an alkaline material such as zinc oxide, it has also been found that the lead salts improve the characteristics of compositions containing, in addition, another filler. The following examples are illustrative of compositions containing a lead salt and another filler in addition to the silicate fiber selected.

EXAMPLE 7 In this example, the effect of a lead salt, for example, tribasic lead sulfate, was observed in a composition compounded with the commercially available grade of asbestos identified as Powminco 25-P in which the resin had the following formulation:

Parts Phthalic anhydride 22.1 Maleic anhydride 36.5 Ethylene glycol 32.5 Sorbo (70% sorbitol) 5 Tertiary butyl catechol 0.28

. Zinc oxide 5.5

A molding composition was prepared with this resin having the following formulation:

Parts Blown diallyl phthalate 23 Resin 89 Powminco 25-P asbestos 62 McNamee clay 124 A. A. Dolomite 62 Zinc oxide 28 Tribasic lead sulfate 12 Calcium stearate 4 Benzoyl peroxide 2.24

A specimen molded from this composition had a heat distortion point of 200 C. as compared to 173 C. for a product made with the commercial composition evaluated in Tables I, II and III. Additionally, the water absorption of the composition of the invention was superior to the commercial molding composition, specifically, 0.12 percent absorption in 72 hours as against 0.17 for the commercial molding composition. At the end of 9 days, the composition of the invention, held at 52.5 C. under nearly 100 percent relative humidity, showed no exudation, while under the same conditions the commercial composition showed bad exudation.

- EXAMPLE. 8

In Table IV are given the exudation and water absorption properties of compositions prepared with various lead salts using a resin prepared from the following formulation:

I Parts Maleic anhydride 31.3 Phthalic anhydride 29.3 Ethylene glycol 30.5 Sorbo (70% sorbitol) 17.6 Tert. butyl catechol 0.28 Zinc oxide 7 Using the resin of the foregoing composition, molding compositions were prepared having the following formulation:

Parts Polyester resin 27 Blown diallyl phthalate Electrical-grade asbestos 66.9 Benzoyl peroxide 1 Lead additive 3.1

Table IV Exudation 1 at 40 0., 95100% RH 72 hrs. Additive Water Composition Absorp- 24 hrs. 72 hrs. 6 days 8 days tion,

Percent None- Very Very Very 0.27

slight slight slight tack. tack. tack. Tribasie lead sulfate. do None Slight Slight 0.18

edges. edges. Dlbasicleadphthaldo... do.. Very Very 0.20

ate. slight slight tack. tack. Dibasic lead phos do en None Slight 0. 20

phite. edges. Dibasicleadstearate. .do .do. Slight do. 0. 17

e ges.

1 Where slight or "very slight are designated, reference is to surface of the disk. In some cases, a tacky surface was noted and the sample is so listed. In other cases, the only effect to be seen was on the edges of disks which had previously been sawed. Thus, slight edges means slight exudate on the sawed edges only.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester and (2) as a filler therefor, acidwashed chrysotile fibers from which essentially all of the reactive alkali has been removed with dilute acid.

2. The molded product of the composition of claim 1.

3. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, and (3) a base of a metal of group H of the periodic system.

4. The molded product of the composition of claim 3.

5. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, and (3) zinc oxide.

6. The molded product of the composition of claim 5.

7. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) a silicate fiber selected from the group consisting of pyroboles and chrysotile, (3) a base of a metal of group II of the periodic system and (4) a lead salt.

8. The molded product of the composition of claim 7.

9. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, (3)

I a base of a metal of group II of the periodic system and (4) a lead salt.

10. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-Washed chrysotile from which essentially all of the reactive alkalihas been removed with dilute acid, (3) zinc oxide and (4) a lead salt selected from the group consisting of tribasic lead sulfate, dibasic lead sulfate, dibasic lead phosphite, dibasic lead phthalate and dibasic lead stearate.

11. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, (3) zinc oxide and (4) tribasic lead sulfate.

12. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, (3) zinc oxide, and (4) dibasic lead phosphite.

13. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, (3) zinc oxide, and (4) dibasic lead phthalate.

14. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of acid-washed chrysotile from which essentially all of the reactive alkali has been removed with dilute acid, (3) zinc oxide, and (4) dibasic lead stearate.

15. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of a pyrobole asbestos, (3) a base of a metal of group II of the periodic system and (4) a lead salt.

16. A molding composition comprising 1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of a pyrobole asbestos, (3) zinc oxide, and (4) a lead salt selected from the group consisting of tribasic lead sulfate, dibasic lead phosphite, dibasic lead phthalate and dibasic lead stearate.

17. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of a pyrobole asbestos, (3) zinc oxide and (4) tribasic lead sulfate.

18. A molding composition comprising (1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-poly hydric alcohol polyester, (2) as a filler therefor, fibers of a pyrobole asbestos, (3) zinc oxide and (4) dibasic lead phosphite.

19. A molding composition comprising 1) as a binder, a polymerizable, unsaturated, polycarboxylic acid-polyhydric alcohol polyester, (2) as a filler therefor, fibers of a pyrobole asbestos, (3) zinc oxide and (4) dibasic lead References Cited in the file of this patent UNITED STATES PATENTS Anderson June 8, 1954 OTHER REFERENCES Mellor: Inorganic and Theoretical Chemistry, 1925, vol. VI, page 426. 

10. A MOLDING COMPOSITION COMPRISING (1) AS A BINDER A POLYMERIZABLE, UNSATURATED, POLYCARBOXYLIC ACID-POLYHYDRIC ALCOHOL POLYESTER, (2) AS A FILLER THEREFOR, FIBERS OF ACID-WASHED CHRYSOTILE FROM WHICH ESSENTIALLY ALL OF THE REACTIVE ALKALI HAS BEEN REMOVED WITH DILUTE ACID, (3) ZINC OXIDE AND (4) A LEAD SALT SELECTED FROM THE GROUP CONSISTING OF TRIBASIC LEAD SULFATE, DIBASIC LEAD SULFATE, DIBASIC LEAD PHOSPHITE, DIBASIC LEAD PHTHALATE AND DIBASIC LEAD STEARATE. 